Bogdan P. Onac

Sea-Level Highstand 81,000 Years Ago in Mallorca

Standing High Sea-level rises and falls as Earths giant ice sheets shrink and grow. It has been thought that sea level around 81,000 years ago—well into the last glacial period—was 15 to 20 meters below that of today and, thus, that the ice sheets were more extensive. Dorale et al. (p. 860; see the Perspective by Edwards) now challenge this view. A speleothem that has been intermittently submerged in a cave on the island of Mallorca was dated to show that, historically, sea level was more than a meter above its present height. This data implies that temperatures were as high as or higher than now, even though the concentration of CO2 in the atmosphere was much lower. Measurements from the island of Mallorca indicate that past sea levels were much higher than had been assumed. Global sea level and Earth’s climate are closely linked. Using speleothem encrustations from coastal caves on the island of Mallorca, we determined that western Mediterranean relative sea level was ~1 meter above modern sea level ~81,000 years ago during marine isotope stage (MIS) 5a. Although our findings seemingly conflict with the eustatic sea-level curve of far-field sites, they corroborate an alternative view that MIS 5a was at least as ice-free as the present, and they challenge the prevailing view of MIS 5 sea-level history and certain facets of ice-age theory.

Reconstruction of climatic and environmental changes in NW Romania during the early part of the last deglaciation (∼15,000–13,600 cal yr BP)

High resolution pollen, plant macrofossil, charcoal, mineral magnetic and sedimentary analyses, combined with AMS 14 C measurements, were performed on multiple sediment sequences alonga transect through the former crater lake Preluca Tiganului in

Minerogenetic mechanisms occurring in the cave environment: an overview

INTRODUCTION Caves are among the longest-lasting components of the environment and throughout their lifespan act as traps, accumulating physical, biological, and chemical deposits. It is well known that the chemical deposits (i.e., speleothems) are by far the most important for the aesthetic value of a given cave. At the same time, fewer people are aware of the fact that natural caves are among the most important minerogenetic environments of our planet. Perhaps man’s first motivation to explore caves was the search for substances that were not available elsewhere. In fact, from pre-historic times up to the present, many caves have been intensively mined. There is evidence that some ~30.000 years ago, humans were already entering caves in search of pigments (mainly iron and manganese oxides and hy-

ASSESSING THE PALAEOCLIMATE POTENTIAL OF CAVE GLACIERS: THE EXAMPLE OF THE SCǍRIŞOARA ICE CAVE (ROMANIA)

ABSTRACT. The ice block in Scarisoara Cave, NW Romania, is preserved due to unusual climate and permafrost conditions within the cave. The air temperature in the cave is governed by the winter cold, the cooling effect of the ice block, and only to a minor extent influenced by summer temperatures. At present, the ice block is slowly thinning, but the present‐day climate is sufficiently cold to preserve the permafrost conditions caused by the cold air trapped in the cave. In February 2003 a 22.5 m long ice core was recovered from the ice block. Approximately 200 ice layers have been identified by visual examination. Ice crystallographic analyses indicate a steady growth of ice crystals with depth and there is no sign of deformation. Carbon‐14 dates on wood‐related samples collected from a natural vertical exposure of the ice block indicate that the ice spans more than 1000 years. Observations on the exposure indicate that a basal melting phase may have occurred in the past.

First reported sedimentary occurrence of berlinite (AlPO4) in phosphate-bearing sediments from Cioclovina Cave, Romania

Abstract This paper describes the first reported occurrence of berlinite (AlPO4) formed entirely under sedimentary conditions. Berlinite appears as grayish or colorless fine crystals in vacuoles and along cracks in heavily compacted, phosphate-rich sediments within the Cioclovina Cave in Romania. The X-ray powder diffraction pattern and the hexagonal unit-cell of the Cioclovina berlinite specimen compare well with other published determinations. The lattice parameters are a = 4.94(4), c = 10.87(1) Å, V = 230.1(3) Å3. Microprobe analyses confirmed a nearly ideal formula for berlinite. In situ guano combustion is responsible for the transformation of taranakite and for the dehydration of variscite into berlinite. Berlinite was successfully synthesized from these two minerals at atmospheric pressure and temperatures ranging from 350 to 600°C

Mineralogy of Cave Deposits on San Salvador Island, Bahamas

Speleothem samples from ten caves located in the northeastern and southwestern corners of San Salvador Island (Bahamas) were analyzed by means of X-ray diffraction, scanning electron microscopy, and the electron microprobe. In addition to the prominent calcite, aragonite, and gypsum, already known to occur in San Salvador caves, eleven other minerals were identified. The minerals are celestite, SrSO4; cesanite, Na3Ca2(SO4)3OH; ardealite, Ca2(HPO4)(SO4)·4H2O; brushite, CaHPO4·2H2O; hydroxylapatite, Ca5(PO4)3OH; fluorapatite, Ca5(PO4)3F; chlorapatite, Ca5(PO4)3Cl; collinsite, Ca2(Mg,Fe)(PO4)2·2H2O; witlockite, β-Ca3(PO4)2; niter, KNO3, and nitratine, NaNO3. Cesanite has not been previously reported from a cave. This is the second reported occurrence of collinsite.San Salvador Island, on the eastern edge of the Bahamian Platform, is the location of a large number of relatively small flank margin caves. In adition TO the more obvious speleothems — stalactites, stalagmites, and flowstone — the San Salvador caves contain a variety of crusts and soils of unknown mineralogy. This paper is an account of an investigation of samples collected from ten of these caves. Prior to the result reported here, only calcite, aragonite, and gypsum had been identified in the various speleothems from caves on San Salvador Island (Vogelet al. 1990; Schwabeet al. 1993).

State of the art and challenges in cave minerals studies

The present note is an updated inventory of all known cave minerals as March 2011. After including the new minerals described since the last edition of the Cave Minerals of the World book (1997) and made the necessary corrections to incorporate all discreditations, redefinitions, or revalidation proposed by the Commission on New Minerals, Nomenclatures and Classification (CNMNC) of the International Mineralogical Association (IMA), we summed up 319 cave minerals, many of these only known from caves. Some of the minerals building up speleothems are powerful tracers of changes in Quaternary climate, other minerals are useful for reconstructing landscape evolution, or allow discriminating between various speleogenetic pathways. Thus, it is expected that the search for new cave minerals will continue and even more attention will be given to those species that carries information that allow for addressing different problems in various earth sciences fields. In view of the exponential increase of cave minerals over the past 50 years, cave mineralogy conceivably has the potential to grow in the future, especially considering the new advances in analytical facilities.

Stable isotope study of precipitation and cave drip water in Florida (USA): implications for speleothem-based paleoclimate studies†

Stable isotopes of hydrogen and oxygen were used to examine how the isotopic signal of meteoric water is modified as it travels through soil and epikarst into two caves in Florida. Surface and cave water samples were collected every week from February 2006 until March 2007. The isotopic composition of precipitation at the investigated sites is highly variable and shows little seasonal control. The δ18O vs. δ2H plot shows a mixing line having a slope of 5.63, suggesting evaporation effects dominate the isotopic composition of most rainfall events of less than 8 cm/day, as indicated by their low d-excess values. The δ18O values of the drip water show little variability (<0.6‰), which is loosely tied to local variations in the seasonal amount of precipitation. This is only seen during wintertime at the Florida Caverns site. The lag time of over two months and the lack of any relationship between rainfall amount and the increase in drip rate indicate a dominance of matrix flow relative to fracture/conduit flow at each site. The long residence time of the vadose seepage waters allows for an effective isotopic homogenisation of individual and seasonal rainfall events. We find no correlation between rainfall and drip water δ18O at any site. The isotopic composition of drip water in both caves consistently tends to resemble the amount-weighted monthly mean rainfall input. This implies that the δ18O of speleothems from these two caves in Florida cannot record seasonal cycle in rainfall δ18O, but are suitable for paleoclimate reconstructions at inter-annual time scales.† Revised version of a paper presented at the 9th, Symposium of the European Society for Isotope Research (ESIR), 23 to 28 June 2007, Cluj-Napoca, Romania.

Re-examination of berlinite (AlPO4) from the Cioclovina Cave, Romania

Abstract Berlinite is a mineral indicative of high-temperature formation and, therefore, it would not be expected to be present in a sedimentary environment. In this study, we review the characteristics of a berlinite-bearing deposit and present a single-crystal structure investigation based on X-ray data: the refinement converged at R1(F) = 0.0276, wR2(F2) = 0.0657 for 677 reflections (2θMoKα ≤ 70°) and 31 variables in space-group P3121 [a = 4.9458(10), c = 10.9526(20) Å, V = 232.0 Å3, Z = 3{AlPO4}]. The average bond distances within the two crystallographically unique TO4 tetrahedra are 1.734 and 1.526 Å, respectively. From the scattering power at these T sites and the stereochemistry, the presence of an AlO4 tetrahedron linked to a PO4 tetrahedron is established. Consequently, the sample from Cioclovina Cave is verified as AlPO4 (modification berlinite), reconfirming the first description of this mineral from a sedimentary occurrence, which underwent an obvious natural heating process.

Hydroxylellestadite from Cioclovina Cave (Romania) : Microanalytical, structural, and vibrational spectroscopy data

Abstract Electron-microprobe analyses of hydroxylellestadite from the Cioclovina Cave (Romania) gave the composition Ca10.27[(SiO4)2.53(SO4)2.17(PO4)1.27]Σ=5.97[(OH)1.66F0.21Cl0.16]Σ=2.03. The mineral is translucent to transparent, light orange, slightly fluorescent, has a vitreous luster and <1.5 mm in length. A singlecrystal X-ray structure investigation gave the average space-group symmetry P63/m [R1(F) = 0.038 for 783 reflections up to 2θMoKα = 70° and 42 variables, a = 9.496(2), c = 6.920(2) Å, V = 540.4 Å3, and Z = 2]. Some atoms exhibit large anisotropic displacements. Ordering of atoms along with a symmetry reduction is not verified. Fourier-transformed infrared (FT-IR) and micro-Raman spectra exhibit a distinct contribution from (PO4)3- modes along with the characteristic (SO4)2- and (SiO4)4- modes. The occurrence is quite unusual and suggests that an intense thermal process affected a restricted area within the cave. Hydroxylellestadite is associated with berlinite, another high-temperature mineral. It is likely to have formed within highly phosphatized, silicate-rich, carbonate-mudstone sediments heavily compacted and thermally transformed due to in situ bat guano combustion.